21 January 2011
Offspring of promiscuous males are more fertile
by George Atkinson 
The contrasting advantages of monogamy and promiscuity have been much debated, and in western society, at least, the long term benefits of monogamy have generally won out. But new research published in the journal BMC Evolutionary Biology shows that sperm from polygamous mice are better competitors in the race for fertilization. Dr Ren�e Firman, from the University of Western Australia, has used house mice to show that sperm from rival males compete to fertilize females and that, over several generations, polygamy can select for mice who produce more sperm, with better motility, than monogamous males. After 12 generations of competitive selection (polygamous) or relaxed selection (monogamous), female mice were mated twice in succession with males from both groups. While 53 percent of the litters had mixed paternity, 33% of litters were fathered by the polygamous males compared to 14 percent by monogamous males.
Polygamous males retained this advantage regardless of whether they were mated first or second, demonstrating that the increased fitness applies to both offensive and defensive competition. The selection procedure had no obvious effect on male size or behavior, nor did it affect female fertility. So in the age old debate about the merits of monogamy versus polygamy is seems that the more partners you have the more fertile your offspring will be. For mice at least. Related:
Monogamy Unnatural in the Natural World
Death By Holy Matrimony
A Short History Of Getting Laid Source: BMC Evolutionary Biology
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